1. Field of the Invention
This application relates in general to a method for forming an antenna structure and in particular to a method for forming an antenna structure on a non-conductive frame.
2. Description of the Related Art
Referring to FIG. 1a, a conventional fan structure usually comprises a hub A and a plurality of blades B surrounding the hub A. When the fan rotates, the blades B can create an axial flow of air. As shown in FIG. 1b, the conventional blade B may have a single curved profile. The air flow can be increased by raising the setting angle a or rotation speed of the fan structure. However, the air flow can be separated from the blade B due to a high setting angle, thus leading to aerodynamic noise and an adverse affect on the efficiency of the fan. Note that the vibration and noise issues may also arise when increasing the rotation speed of the fan.
In a conventional fan structure, a high air pressure gradient usually occurs in an outer local region of the blade, such as the region D1 shown in FIG. 1c. Since the region D1 is not averagely distributed on the blade, eddy flow and separation of the air flow from the blade may occur, thus adversely reducing aerodynamic efficiency of the fan.